1. Technical Field
The present invention relates to a severing machine for cutting rolls or logs of great length into a plurality of small rolls intended for final consumption, or for cutting other elongate products, especially of weblike material, for example packs of paper napkins or other interleaved articles.
Machines of this type are commonly used in the paper converting industry for the production of rolls of toilet paper, rolls of kitchen paper and the like, or other paper articles.
2. State of the Art
In the paper converting industry, and especially in the production of products comprising tissue paper, provision is commonly made for the weblike material to be wound up into logs or rolls of large axial dimensions and diameter equal to the diameter of the finished article. These logs or rolls are subsequently cut into a plurality of small rolls, of axial dimensions equal to the final dimension of the article intended for consumption, by means of severing machines.
Typically, in order to perform the cutting of the rolls, use is made of severing machines which possess an assembly rotating or oscillating about a shaft and on which are mounted one or more disk-shaped blades controlled in rotation about their respective axes. The movement of the assembly brings the disk-shaped blade(s) mounted thereon to penetrate cyclically into the material forming the roll, which is caused to advance below the rotating assembly. At each cycle of the rotating assembly, at least one small roll is cut from each of the rolls being fed. Normally, a plurality of rolls are caused to advance in parallel and are cut simultaneously with successive passages of the same disk-shaped blade carried by the rotating or oscillating assembly. When the assembly carries two blades, two cuts are made during each cycle.
An example of a severing machine of this type is described in U.S. Pat. No. 5,522,292.
According to another known technology, provision is made to cut each roll into the final number of small rolls in a single pass by means of a series of parallel cutting blades. A severing machine of this type is described in U.S. Pat. No. 4,329,895. In this machine, the rolls to be cut are inserted into cradles which advance in a linear manner below a plurality of parallel rectilinear blades inclined relative to the direction of advance of the rolls. The blades all penetrate together and gradually into the material of the roll, cutting the latter into a series of small rolls during a single pass.
Another example of a severing machine which allows the simultaneous cutting of each roll into a plurality of small rolls is described in IT-B-1 103 635. In this known machine, a rotating assembly presents the individual rolls, which are accommodated in respective seatings, to a set of rotating blades. The rotating blades have a shape such as to penetrate gradually with their cutting edges into the thickness of the rolls.
Both the multiple cutting machines currently known and the machines that use blades equipped with a planetary motion to xe2x80x9cslicexe2x80x9d the rolls fail to meet the current safety standards. Furthermore, the multiple severing machines currently known suffer from problems with sharpening the blades.
It is an object of the present invention to provide a multiple severing machine, in other words a machine equipped with a plurality of cutting blades for simultaneously cutting a plurality of small rolls from a roll or log fed to the machine, or for cutting other elongate products into series of articles of lesser length, which is safer than the traditional machines and can permit a reduction in the contamination of the cut article.
This and other objects and advantages, which will become apparent to the persons skilled in the art from reading the text that follows, are achieved by a severing machine comprising at least one series of disk-shaped blades rotating about their own axes of rotation, in which the series of blades is carried by a moveable support capable of displacing said series of blades alternately into an active or cutting zone and into a parking zone, and in which a barrier is provided separating the active or cutting zone from the parking zone in which sharpening of the blades may be carried out, so that the dust and other contaminants deriving from the sharpening are retained in the parking zone and their penetration into the active zone is impeded.
In what follows, the active zone will be designated the cutting zone and the parking zone as the sharpening zone, although other operations may also be carried out therein (as will be clarified below).
The barrier which separates the sharpening zone from the cutting zone also serves to prevent the sparks generated during sharpening from being able to trigger dangerous fires on reaching the weblike material of which the rolls being cut are formed. This risk is particularly high in the traditional machines where the sharpening zone is situated directly above the cutting zone and is in no way separated therefrom. The risk of fire is particularly great by reason of the presence of dusts of paper or other highly flammable material from which the rolls are formed, which dusts are formed during cutting and may be impregnated with lubricant. With the barrier provided by the present invention, the flammable dusts are kept separate from the sharpening zone (where sparks are generated) and the operating safety is thus increased. A further technical safety advantage is represented by the possibility of maintenance work being carried out in the parking zone, cut offxe2x80x94by the barrierxe2x80x94from the cutting zone.
According to an advantageous embodiment of the invention, the support on which the cutting blades are mounted has an elongate development in the form of a beam along an axis of oscillation or rotation. The support can rotate or oscillate about this axis in order to move the series of blades from the sharpening zone to the cutting zone and vice versa.
In order to achieve high production speeds, and also to balance the mechanical structure of the machine, according to a particularly advantageous embodiment of the invention, a second series of disk-shaped cutting blades is provided, arranged on the support, in a manner such that when one of the two series of blades is in the cutting zone the other is in the sharpening zone and vice versa.
The possibility is not ruled out that more than two groups or series of cutting blades are arranged on the same support. The use of at least two series of cutting blades makes it possible to carry out the sharpening operation or other auxiliary operations during the cutting operations. Furthermore, it is possible to provide for the various series of disk-shaped cutting blades to be arranged at different intervals, so as to enable articles of different axial dimensions to be produced with the same severing machine without intermediate setting operations.
The use of two or more groups or series of blades can allow the rapid replacement of an entire group with another group when the former is in non-operating conditions, for example when the blades are worn.
In order to separate the sharpening zone from the cutting zone, barriers of various types may be provided, for example flexible, sliding or other barriers. According to a particularly advantageous embodiment of the invention, however, the barrier comprises two walls oscillating about axes parallel to the axis of oscillation or rotation of the support on which the one or more series of blades is or are mounted. The two oscillating walls interact with the support to form a separation barrier between the cutting zone and the sharpening zone, bearing, with the edges opposite the axis of oscillation, on the support bearing the cutting blades.
In the zone isolated by the barrier, devices for washing the sharpened blades may be provided in order to remove all of the sharpening dusts. Where there are three or more groups of blades, the washing devices may be arranged in a station separate from the sharpening station and possibly isolated therefrom by means of a further barrier.
Further advantageous features of the severing machine according to the invention are indicated in the attached claims and will be described in detail with reference to examples of embodiment.